Commercial production of pure carbonic dioxid.



No. 65|,569. Patented lune l2, I900.

H. HOWARD.

COMMERCIAL PRODUCTION OF PURE CARBONIG DIUXID.

(Application filed Dec. 9, 1899.)

(No Model.)

UNITED STATES PATENT O FI E.

HENRY HOWARD, or BRooKLINE, MASSACHUSETTS.

COMMERCIAL PRODUCTION OF PURE CARBONIC DIOXID.

. SPECIFICATION forming part of Letters Patent No. 651,569, dated. June 12, 1900. Application filed December 9, 1899. Serial No. 739,754. (No specimens.)

TO (1.56 ivhom it may concern:

Be it known that I, HENRY HOWARD, of

Brookline, county of Norfolk, State of Mas-' saehusetts, have invented an Improvement in Commercial Production of Pure Carbonic Dioxid, of which the following description, in connection with the accompanying drawing, is a specification, like numerals on the drawing representing like parts;

This invention has for its object the com- ..mercial production of pure carbonic dioxid (CO in a rapid and economical manner, whereby by a simple and continuous process the CO is obtained in a perfectly-pure condition at a low cost.

In theordinary process of manufacturing bisulfite of soda (NaHSO,) a solution of sodaash is saturated with SO until the bisulfite is formed, and during the process two reac tions take place:

If pure SO were used, we would have pure C0 evolved by (l); but on account of the much greater cost of pure SO it is necessary to use, commercially, a cheaper, more dilute, and more impure source of S0 and this is conveniently found in the gas evolved from burningsulfur or pyrites or similar ,compounds. This burner-gas, asit is termed,

rarely tests over eleven per cent. of S0,, theremainder being made up of nitrogen and an excess of oxygen, and burner-gas from fectly-pure CO as a by-product,. although the source of the S0 in the chemical reactions is burner-gas, as hercinbeforc mentioned. V

The drawing, in side elevation, shows one Upon a suitable framework 50 are erected tanks 3, 8, and 9, the former having a gastight cover and being also elevated above the tops of the tanks 8 and 9, a sulfur-burner -(indicatedat 1) communicating with the lower portion of the tank 3 by a pipe 2 to conduct burner-gas to the tank, the pipe being carried up at least as high as the top of the tank, as at 30, to prevent passage ofv the liquid contents of the tank into the pipe. A suitable suction-pump 5 communicates by pipe 4 with the upper part'of the tank 3, the pump-exit being shown at 6. In the tank 3 I have a batch of bisulfite formed, as, will be described, and twice as large, preferably, as I wish to produce at a time, and one half of the batch is run into the smaller tank 8, and after settling it is ready for the market, and the bisulfite can be drawn ed at 10. The other half of the batch is run into the tank 9, the discharge-pipe 7 having valves and 71 to control the passage of contents of tank 3 to tanks 8 and 9, respectively. A'

conduit 15, having a suitable controllingvalve 150, leads from tank 9 to'the CO generator 14, a covered tank having about the capacity of tank 3 and preferably set below tank 9, so that the contents of the latter will discharge by gravity through conduit 15. This generator 14 contains a preferably' -hot solution of soda-ash, (Na,CO,,) and into it the contents of tank 9 are rlin slowly, the following reaction taking place:-

The solution is kept at boiling temperature in the generator 14 to prevent any. material amount of CO, from remaining in aqueous solution. Any suitable device is employed for heating the solution in the generater, such as a coil of steam-pipes, the inlet therefor being shown at 16, the steam being taken from any suitable source. The carbonic dioxid (C0,)thus driven oil .from the generator ll is separated from the steam by a condenser 80, having an inlet 81 for cold water and an outlet 89 for the heated water after circuladenser from the generator, and the cold C is then washed with a soda solution in a scrubber 18 of common construction to remove any traces of SO orsulfites which might possibly have escaped during reaction (3) or have been carried over mechanically. The pure CO coming from the scrubber is now ready for pump 20 and thence delivered by a pipe 21 to the tank 3, which may be termed the converter, as the neutral-sulfite solutionis therein converted into bisulfite-of-soda (NaHSO solution by 80,, preferably produced in the sulfur or pyrites burner 1.

The generator 14 and scrubber 18 are of course gas-tight, while the tanks 8, 9, and 11 have open tops, the soda-ash being dissolved in the latter tank, a pump 12' drawing the solution therefrom and pumping the charge to the generator through pipe 13, the various pipes and conduits of the apparatus in practice being provided with suitable valves for controlling the flow theret-hrough.

The vacuum-pump 5 produces a partial vacuum in the converter 3,causing the burnergas to bubble up through the solution therein and furnishing draft for the burner, the ni-' fite directly the other half is transformed into .neutral sulfite with the evolution of pure (10 after which it is reconverted into bisul-' lite to form a fresh charge, the process being continuous in character.

Either the carbonate or bicarbonate of soda may be used, and if the latter is used the amount of CO obtainable as a by-product in the manufacture of a given amount of hisulfite of soda will be doubled, the reaction being l The sesquicarbonate of soda may also be used or mixtures of the different carbonates of soda,

, in practicing my invention.

1. In the production of pure CO transforming bisulfitc of soda into neutral sulfite by the action of a sodium carbonate in the presence of H 0, with the evolution of C 0 withdrawing the latter, and converting the remaining neutral sulfite into bisulfite ofsoda by saturation with S0,.

2. The process of producing pure CO from carbonate of soda by a weak or. dilute S0 gas, which consists in converting neutral sulfite of soda into bisulfite by the action of weak S0 gas in the presence of water, to form a carrier for the S0 eifecting the mixture of the said carrier with a sodium carbonate,with the evolution of pure 00 and separating the latter, leaving neutral sulfite of soda.

3. The herein-described process of produciug pure CO consisting in adding bisulfite of soda to a solutionof a sodium carbonate; boiling the mixture to drive off 00 therefrom, and separating the aqueous vapor from the CO by condensation.

4. The cyclical process of producing'pure (30,, consisting in adding bisulfite of soda to a sodium carbonate in the presence of H 0; boiling the mixture to drive ofif CO separating the aqueous vapor therefrom by condensation; adding S0 to the neutral-sulfite solution (Na SO to form bisulfite of soda, and continuing theprocess.

5. The process of producing pure CO in the manufacture of bisullite of soda, which consists in dividing a charge of bisulfite solution, and transforming oue portion thereof into neutral-sulfite solution by the action of a sodium carbonate, with the evolution of one half of the same as commercial bisulfitev of soda; subjecting the other half to the action of a sodium carbonate and boiling to drive off (10,; separating the-aqueous vapor from the latter by condensation; converting the remaining neutral sulfite of soda into bisulfite by the action of SO in the presence of water, to form a new charge, and repeating the steps as set forth.

7. The process of recovering pure CO in the continuous manufacture of bisulfite of soda with burner-gas and a sodium carbonate, which consists in converting neutral sulfite of soda into bisulfite by saturation with SOg'flOlIl burner-gas in the presence of water; dividing the charge of bisulfite so formed, and separating one portion thereof ascommercial bisnlfite; subjecting the other portion to the action of a carbonate of soda, to form neutral sulfite with the evolution of pure CO sep 1 arating the latter, and finally converting the fore, to form a fresh charge.

v 8. The herein-described process of preducnameto this specification'in the presence of ing pure CO consisting in bringing together two subscribing witnesses. bisulfite of soda and a solution of a sodium '7 T carbonate in a closed vessel to prevent access HENRX 5 of air, and withdrawing the CO evolved by Witnesses:

such mixture. JOHN C. EDWARDS, In' testimony whereof I have signed my EMMA J. BENNETT. 

